Who is blocks biloxi?

"Blocks" Biloxi is a character mentioned by Daisy Buchanan in The Great Gatsby. When remembering her wedding, she remembered that Biloxi had fainted.

The significance of this is to emphasize the flakiness of Daisy's character who, instead of remembering her ceremony, remembered such an insignificant event. It also outlines her lack of value for the wedding and her lack of "love" for Tom, as she remembers this pointless event.